GuideTechnology
18 min read
Replace nested loops with two indices that move in a controlled way. Learn the opposite-ends and same-direction patterns, why each pointer move is safe, and solve pair sum, container with most water, 3Sum and in-place deduplication.
GuideTechnology
22 min read
Linear and binary search done right (invariants, boundaries and overflow-safe midpoints), lower and upper bound, searching on the answer, the main sorting algorithms and their trade-offs, and how to sort anything in Java with comparators.
GuideTechnology
21 min read
How a heap keeps the smallest or largest item ready in O(1), how insert and remove work in O(log n), how to use Java's PriorityQueue, and how to solve top-K, k-th largest and merge-k-sorted problems. Includes how a heap differs from a BST.
GuideTechnology
22 min read
Tree vocabulary, the four traversals (preorder, inorder, postorder, level-order), recursive and iterative code, and binary search trees: search, insert, and the right way to validate one.
GuideTechnology
24 min read
Learn to think recursively: base cases, the call stack and recursion trees. Then use backtracking (choose, explore, undo) to generate subsets, permutations and combinations, avoid duplicates, prune the search and solve N-Queens.
GuideTechnology
20 min read
How hash tables find things almost instantly, what collisions are, how to use HashMap and HashSet in Java, and the patterns that solve duplicates, two-sum, grouping and counting problems. Includes the equals and hashCode contract.
GuideTechnology
19 min read
Last-in-first-out and first-in-first-out, explained with real examples. Learn the right Java collections (ArrayDeque, not Stack), then solve bracket matching, round-robin scheduling and next-greater-element with a monotonic stack.
GuideTechnology
20 min read
Build singly and doubly linked lists from scratch in Java, learn to reason about pointer changes step by step, and solve reversal, middle-finding, merging and cycle detection with clear diagrams and dry runs.
GuideTechnology
17 min read
How Java strings really work: characters and codes, comparison, immutability and StringBuilder, then the classic problems (palindromes, anagrams, run-length encoding) plus honest notes on Unicode.
GuideTechnology
20 min read
How arrays work in memory, why indexing is instant but inserting is slow, and how to solve the classic array problems: maximum, frequency counting, in-place rotation, moving zeroes and subarray sums.
GuideTechnology
19 min read
Big O explained by counting steps: constant, logarithmic, linear, n log n, quadratic and exponential growth, best, average and worst cases, auxiliary and recursion-stack space, with dry runs you can check yourself.
GuideTechnology
21 min read
Only the Java you need for data structures and algorithms: types and overflow, loops, methods, arrays, strings, a small class, input and output, and the mistakes that trip up almost every beginner.
GuideTechnology
17 min read
How to turn a vague problem statement into a clear plan: pin down inputs, outputs and constraints, list edge cases, write pseudocode, build a brute-force answer first and then improve it.
GuideTechnology
15 min read
What data structures and algorithms are, why employers test them, what you can honestly expect from this free 28-article course, and the repeatable six-step loop you will use on every problem.
CourseTechnology
28 lessons · 9 h
A free, 28-article course that takes you from basic problem solving to independently approaching common interview problems in Java. It explains each idea first, shows it in code you can run, and ends with exercises, solutions, an interview workflow and a study plan.
GuideTechnology
5 min read
Most disappointing AI answers come from vague questions. Learn a simple structure for prompts, how to give context and examples, how to iterate, and how to check what comes back.
GuideTechnology
6 min read
APIs are behind every UPI payment, map pin and login-with-Google button. Here's what they are, how a request actually works, and how to call one yourself in five minutes.
GuideTechnology
5 min read
Frontend, backend, full-stack: the options are confusing. This roadmap sorts the roles, shows what to learn and in what order, and ends with projects and a job-hunt plan.
GuideTechnology
6 min read
AI assistants can save you hours a week, and one careless paste can leak customer data or put a confident mistake in front of your manager. A practical guide to using them well.
GuideTechnology
5 min read
AI can be a patient tutor, a quiz master and a writing coach, or a shortcut that leaves you knowing nothing. Here is how to use it to learn faster, with prompts, routines and rules that keep you honest.
GuideTechnology
5 min read
SQL is the language for asking questions of data, and it is one of the most useful skills to learn. This guide walks through SELECT, WHERE, GROUP BY, JOIN and more, with a small example database.
GuideTechnology
5 min read
Python is the most common first language, but most beginners get stuck in tutorials. This roadmap shows what to learn in order, which projects to build, and how to go from basics to a job-ready skill.
GuideTechnology
5 min read
Machine learning lets computers learn patterns from data instead of following hand-written rules. Here is what it is, the main types, the maths and programming you need, and a realistic learning path.
GuideTechnology
6 min read
If AI can write a working function in seconds, is learning to code still worth it? Yes, but the way you learn needs to change. A practical roadmap for beginners in 2026.
GuideTechnology
5 min read
DSA is the most feared part of software interviews. The fear mostly comes from learning it badly. Here is a calm, pattern-based way to learn it, with a topic order, daily habits and ways to retain what you solve.
GuideTechnology
4 min read
JavaScript runs every website, but its ecosystem overwhelms beginners. This roadmap shows what to learn first, what to postpone and which projects prove you can build.
GuideTechnology
7 min read
Random changes and hopeful refreshes waste hours. This is a step-by-step debugging process that works in any language: reproduce, narrow down, form a hypothesis, test it, then fix the cause.
GuideTechnology
5 min read
AI chatbots feel like magic, but the basic idea is simple: they predict the next piece of text, based on patterns learned from huge amounts of writing. Here is how that works and why they sometimes get things wrong.
GuideTechnology
5 min read
What really happens in the second between pressing Enter and seeing a page? A plain walk through DNS, servers, HTTP, HTML, CSS and JavaScript, with no jargon left unexplained.
GuideTechnology
5 min read
Git looks scary because of its long command list. In daily work you use about ten of them. This guide explains the idea behind Git, then walks through the everyday workflow, branches, and how to undo mistakes.
